compliant mechanism design

This work addresses the challenges of excessive actuation dimensionality and complex shape control in reconfigurable tendon-driven continuum robots, which arise from tendon rerouting. To circumvent the need for intricate dynamic modeling, the authors propose an actuation space reduction method that maps the backbone configuration into an intermediate curvature–torsion space to identify critical actuation disks. By integrating a rerouting mechanism based on actively rotated spacer disks and employing a proximal-to-distal staged shape-matching strategy, the approach effectively approximates the global configuration while enabling fine distal adjustments. This methodology significantly enhances the intuitiveness and efficiency of shape control without relying on complex kinematic or dynamic models.

This work proposes a tendon-driven continuum robot featuring a tapered flexible backbone fabricated from thermoplastic polyurethane (TPU), addressing limitations of conventional designs—such as high cost, poor customizability, and the difficulty of simultaneously achieving high curvature and distal compliance—in flexible manipulation tasks. An integrated electronic base enables precise tendon tension control and sensing. For the first time, the spatially varying tapered cross-section is explicitly incorporated into a forward dynamic-static model based on Cosserat rod theory to capture the influence of geometric tapering on stiffness distribution. Leveraging fused deposition modeling 3D printing and parametric CAD design, the system achieves low-cost, rapid assembly, and high customizability. Experimental calibration demonstrates centimeter-level shape prediction accuracy, and successful teleoperated endoscopic grasper tasks validate the robot’s efficacy in complex flexible manipulation scenarios.

To address the challenge of achieving both high load capacity and adaptive compliance in tendon-driven underactuated fingers, this paper proposes a compact, single-actuator design featuring full-joint mechanical coupling. A novel fixed-ratio synchronous tendon routing mechanism enables predictable stiffness and underactuated kinematic constraints while ensuring whole-finger unified actuation. We develop a static and kinematic model incorporating tendon elasticity and validate it experimentally using a 3D-printed prototype: under a 3 kg fingertip load, the finger achieves a stiffness of 1.2×10³ N/m, with deformation prediction error of only 1.0 mm (0.322% of finger length). This design significantly reduces complexity and weight in multi-fingered robotic hands; integrated into a five-fingered hand, it successfully accomplishes stable, adaptive grasping of diverse objects.

To address the conflicting challenges of low kinematic fidelity, insufficient rotational stiffness, and significant parasitic motion in large-angle (±15°) flexible crossed-hinge mechanisms, this paper proposes a static-dynamic-driven multi-objective optimization design methodology. We innovatively integrate rapid Euler–Bernoulli beam modeling with high-fidelity 3D ANSYS finite-element refinement to establish an interpretable hybrid modeling framework. Coupled with the NSGA-II algorithm, this approach efficiently explores the high-dimensional design parameter space and yields a Pareto-optimal solution set. The optimized configuration achieves motion error <0.5° over ±15° rotation, enhances rotational stiffness by 3.2×, and suppresses parasitic displacement by 87%, substantially outperforming conventional designs. This work provides both theoretical foundations and an engineering paradigm for high-performance compliant mechanisms.

This study addresses the challenges of conventional wrist exoskeleton actuation mechanisms—namely excessive weight, high friction, and structural complexity—by proposing a novel abduction–adduction actuation mechanism based on a single tendon cable coupled with a helical torsion spring for passive tensioning. The design leverages Bowden cable transmission and a clock spring to achieve self-tensioning without requiring antagonistic actuation. Kinematic and dynamic modeling guides the selection of spring stiffness, thereby reducing reliance on empirical tuning. Experimental validation demonstrates strong agreement between simulation predictions and actual performance trends, with the chosen spring configuration achieving a balanced trade-off among range of motion, output torque, and repeatability. These results effectively support the development and optimization of lightweight, compact cable-driven wrist exoskeletons.

This study addresses the limitations of conventional rolling robots, whose joint mechanisms are typically complex and lack tunable stiffness, thereby struggling to balance adaptability, safety, and energy efficiency. To overcome these challenges, this work proposes SPiralRoll, an underactuated compliant joint based on an arc-shaped torsion spring. By integrating dual-motor actuation with a nonlinear elastic deformation mechanism, SPiralRoll enables coupled three-degree-of-freedom motion—rotation, radial expansion/contraction, and axial self-rotation. Notably, this design represents the first application of arc-shaped torsion springs in rolling robot joints, offering advantages such as adjustable stiffness, full 3D printability, and low cost. Experimental results demonstrate that the full-arc configuration provides strong structural support, while the single-arc variant exhibits large deformations and pronounced actuation effects, successfully propelling a spherical robot in both forward locomotion and steering maneuvers, thus validating the feasibility and effectiveness of the proposed compliant joint for rolling robots.

This study addresses the challenge of achieving both lightweight design and fault-tolerant reliability in space robotic arms under stringent mass constraints. The authors propose an innovative architecture based on time-division multiplexed actuation (TDMA), integrating a vertically stacked rotary gating mechanism with self-rotating TDM motors, electromagnetic clutches, worm-gear reducers, and a dual-encoder system. This integration significantly reduces the number of actuators while enabling sub-0.1-second clutch response, inherent self-locking capability, and high-precision positioning. A complementary trajectory planning algorithm ensures fault-tolerant control even under partial servo failure. The resulting MuxArm prototype weighs only 2.17 kg, can manipulate a 10 kg payload, achieves end-effector positioning accuracy within 1% of arm length, and reduces tendon loading by 50%.